add triage/needs-confirmation to collector (#55189)

.github/metrics-collector.json

@@ -16,6 +16,10 @@
       "name": "needs_more_info",
       "query": "label:\"needs more info\" is:open"
     },
+    {
+      "name": "triage_needs_confirmation",
+      "query": "label:\"triage/needs-confirmation\" is:open"
+    },
     {
       "name": "unlabeled",
       "query": "is:open is:issue no:label"
@@ -23,10 +27,6 @@
     {
       "name": "open_prs",
       "query": "is:open is:pr"
-    },
-    {
-      "name": "milestone_7_4_open",
-      "query": "is:open is:issue milestone:7.4"
     }
   ]
 }